Gas lift pump



Sept. 6, 1938. J. E. HOOVER GAS LIFT PUMP lFiled Janl 29, 1956 2Sheets-Sheet 1 J. E. HOOVER GAS LIFT PUMP Sept. .6,` 1938;

Filed Jan. 29, 1936 2 Sheets-Sheetl 2 INVENTOR.l I JAMES E. HOOVERATTORNEYS.

Patented Septc 69 `1938 einem Unirse STATES PATENT orales GAS LIFT PUWJames E. Hoover, @Mahoma City, Ghia.

Application January 29, i936, Serial No. 61,393

1l Claims.

This invention relates to apparatus for raising liquids from wells.

More specically the invention relates to an improved gas lift pump forraising liquids such as oil or water from deep wells.

A further object of the invention is the provision of a device whichwill raise a volume of liquid from a well with a satisfactory gas-liquidratio.

be used to operate the apparatus.

Liquids, compressed air, compressed vapors, etc., are contemplated asactuating lfluids.

It is the usual practice upon cessation of normal flow from a wellresulting from a diminution of the rock pressure existing in theproducing strata or reduced gas content of the fluid within theformation, to employ a gas lift to sustain and increase the flow orproduction of the well.

The gas lift method, either continuous or intermittent, as will beunderstood by one skilled in the art, comprises the introduction of agas, generally under pressure, into the well to aid the oil flow byaerating or lightening the fluid column and thereby enabling the loweredrock pressures existing at that time to overcome the hydrostatic head ofthe uid column and thereby to continue the flow.

face.

It has been the general practice in the past to employ a pumping deviceof the so called sucker rod type. .The limitations of a pump of thistype are Well recognized in the art.

In deep wells structural limitations are encountered because of thestretch inherent in any steel which will resist the corrosive effects ofthe fluids encountered in the Well.

A second limitation of a serious na- (Clu HB3-240) ture is the size'andWeight of the machinery at the well surface necessary to reciprocatemany thousands of feet of sucker rod of sufficient size to sustain itsown weight and a column of liquid of equal'length.

A third limitation of considerable importance is the sand cutting ofpumps of this type. After a well has ceased to flow naturally undernormal rock pressures or under the gas lift method, the remaining gaspressure from the producing formation is sufficient in many instances tomaintain the liquid in an agitated condition with the result thatconsiderable sand will be contained in suspension in the liquid. Thissand exerts a very detrimental abrasive action upon the pumping elementswith which it comes in Contact. because it is under the largehydrostatic head of the liquid column. It therefore is obvious thatmoving parts requiring fairly close fits soon will become worn to anextent that they are no longer serviceable. The pump then must be pulledfrom the well, at great expense, for repairs.

In applicants device the pump is actuated by gas under pressure from thewell surface. The only direct connections to the surface which must bereciprocated are light rods whose sole funcn tion is to operatepositively the pump valves. lt is apparent that the structurallimitations encountered in the sucker rod pumps are not present inapplicants device because the rods do not sustain any oil load or heavypumping elements.A

Further advantages of applicants construction will be evident from aconsideration of the specilication and claims in connection with theanneXed drawings wherein: Y

Figure 1 is a longitudinal view of applicants device in place in a well,partly in section.

Figure 2 is a longitudinal sectional view taken on the line 2--2 ofFigure 3, of one embodiment of applicants device.

Figure 3 is a cross-sectional view takenv on the line 3--3 of Figure 2.

Figure 4 is a longitudinal sectional View of a device for reciprocatingthe valve actuating rod.

Figure 5 is a longitudinal sectional View of a second embodiment ofapplicants device taken on the line 5-5 of Figure '7.

Figure 6 is a longitudinal sectional view of still another embodiment,and

Figure 7 is a cross sectional view taken onthe lines 'lof Figures 5 and6.

It should be understood that applicant has shown certain `preferredembodiments of his device in the drawings for thepurposes of illustra-Aas tion only and that other devices within the scope of the appendedclaims are anticipated.

Also, applicants device is not limited to use inr oil or water wells ofthe type shown, but may be used in other wells for raising other liquidswhere it is considered desirable.

Referring to Figure 1, a well casing of conventional design is shown at20. This casing is lowered and set in the well hole by the usual methodsand generally extends down to the edge of the producing strata III andcemented therein as at II, as is well understood by those skilled in thedrilling art.'

A string of tubing 2| of smaller diameter than the casing 20' is thenlowered therein. A second tubing string 32, which is mounted in spacedrelation with the tubing string 2|, carries at one end thereofapplicants improved pumping device, generally indicated at I2, and issealed at the other end as at I3. A pipe I4 for the induction ofactuating gas is mounted adjacent to and in communication with one endof the tubing string 2|.

A pipe I is in communication with the induction tube 32 and may serve toconduct pumped iiuid from the well, or operating gas to the pump, aswill appear later. A machine is generally indicated at 64 forreciprocating the valve actuating rods as will be subsequentlydescribed.

Referring more particularly to Figure 2, a bull Plug 22 slotted as at 23is fixed to the lower open end of the tubing string 2| as by screwthreads 24 or by other conventional means, and rests upon or is adjacentto the bottom of the well hole and below the normal liquid leveltherein. A valve cage 25 is secured -as by screw threads 26 within thelower end of the tubing 2l and adjacent the bull plug 23. A standingvalve 21 which may be in the form of a ball is located within the cage25 and normally closes the aperture 28 of its own weight. Apertures 29in the cage 25 provide for the passage of liquid from the well throughthe cage when the valve is in a raised position.

Applicants pumping element, generally indicated by the numeral I2, issecured to a tubing string 32 as by screw threads 33, and is loweredinto the well by means of the tubing 32 which, in addition, forms aconduit for the removal of liquid to the surface.

A conical shoulder 34 is formed intermediate the length of the pump body3| and cooperates With a seat 30 on the tubing string 2|, located at apoint above the maximum liquid level in the well hole, to form a. sealedchamber 35 for the accumulation of liquid from the well.

' It will now be apparent that any liquid standing or flowing into thewell hole will raise the standing valve 21. and pass into the chamber35.

against the weight of the standing valve which is so chosen thatrelatively little pressure is required to operate it.

The pump lbody I2 comprises a casing 36 of generally cylindricalconfiguration, mounted within and spaced from the tubing 2| except atthe seat portions 30 and 34 thereby providing spaced annular chambers asat 51 and 5,8. Attached to the lower extremity of the casing 36 is areducer 31 at one cnd of which is provided a valve cage 36 containing astanding valve 39 through which liquid within the chamber 35 may pass,under pressure, into the valve casing 36. Mounted within the valvecasing 36, as by screw threads 40, is a valve cylinder or chamber 4|,provided with gas Aadmission passages 42 and liquid passages 43,

shown in Figures 2 and 3, located in an enlarged head 44 of the valvesleeve 4 I.

Gas admission ports 45 are shown in the side walls of the enlargedportion of the Valve cylinder 4| and in communication with the gasadmission passages 42, and may be formed by drilling entirely throughthe enlarged head 44 and then plugging the aperture in the outercylinder wall as by screw plugs 46. Other methods of forming the ports46 will be obvious to those skilled in the art. Other ports 41, 48 and49 are positioned in the valve cylinder 4| at definite locationsdepending upon the functions to be performed, as will appear later.Similar ports or apertures 50, 5| and 52 are provided in the Wall of thevalve casing 36 and in alignment with the ports 41, 48 and 49 formed inthe valve cylinder. Tubular elements 53, 54 and 55 place the ports 41,48 and 49 in communication, respectively, with the apertures 50, 5| and52. It will be noted that the apertures 50 are located in the conicalseat element 34 of the casing 36. A passage 56 is provided through theseat 36 on the tubing 2| and in alignment with the aperture 50. Anannular groove 56' of larger cross sectional area than the passages 56and interconnecting the inner ends of the same is provided in the innerwall surface of the seat 30, whereby the passages 56 will be incommunication with the ports 50 through the groove 56 in any relativecircumferential position of the valve casing 4| within the tubing 2|. Itis also apparent that the groove, because of the aforementioneddifference in cross sectional area, provides for slight longitudinalmisalignment of the ports 50 and passages 56 due to any inaccuracies inthe machining of the seats 30 and 34.

It will now be apparent that the valve cylinder 4| may be placed incommunication with the passages 42 through the ports 45; with theannular space 59, between the tubing 2| and casing 20, through the ports41, tubes 53, groove 56 and passage 56; and with the chamber 35 throughthe ports 48 tube 54 and aperture 5| and through the port 49, tube 55and aperture 52.

A valve piston shown at 66 is slidably received within the valvecylinder-4I and has a fit suiciently snug to form an efficient seal, orif desired, suitable packing rings, not shown, may be employed. A plug6| is suitably secured in the upper end of the piston 60, asbyscrewthreads 62, in which a rod 63 is fixed in any convenient manner.Rod 63 extends to the top of the well and may be reciprocated by thedevice shown generally at 64, as will be developed later.

Spaced ports 65 and 66 are provided in the wall of the piston 60 whichin turn communicate with annular grooves 65' and 66 formed in the outersurface of the piston. It will be noted that the grooves are larger incross-sectional area than the ports and are continuous to provide forcontinuous communication regardless of circumferential or longitudinalmis-alignment as previously described.

This valve piston 4I controls the flow of an actuating iiuid such as gasor other suitable medium, and to this end the ports 65 and 66 are sospaced that in certain positions of the piston these ports are in1communication with certain of the ports in the valve cylinder 4|. Withthe valve piston at the upper limit of its travel, the positionindicated in Figure 2, it will be observed'that the port 48 is incommunication with the port 45 through the ports 66 and 65 and a chamber61 formed in the piston 4|. It will be apparent that in the positionshown, a fluid under pressure withtiti aiaaoco in the tubing 2l may passthrough the passages d2, port t5, piston port 65, chamber t'l, pistonport B6, a tube 5d, aperture 5| and annular space 5b to the liquidaccumulation chamber 35. Also, with the piston at the other extremity ofits travel, ports tb and t5 will be Ain communication with ports tl andt@ respectively, thus providing for the passage of trapped gas in thechamber t5 through the aperture 52, tube 55, portt, port tti, chamberlil, port t5, port 4l., tube 53 and passage 5t to the annular space 59between the tubing ti and casing til.

The valve piston t is operated ina positive manner from the welllsurface by means of the rods tt which are actuated by a machinegenerally indicated at t4, located at the well surface.

The machine till comprises a cylinder lit provided at one end with astuffing box tt of any conventional construction, through which the rod@t slidably passes. d piston it provided with sealing grooves 'il isslidably mounted within the cylinder tit and the rod t3 is connected tothe piston liti by means of a wrist pin l2. An inlet pipe itcommunicates with the cylinder for the conveyance of a fluid underpressure thereinto which may be controlled by any suitable valvc means,not shown. A bleeder passage 'lit and an exhaust pipe 'lli is formed inthe piston llt and an end wall 'it of the cylinder, respectively. lnpractice, it may be desirable to attach the cylinder lid directly to theend of the gas induction tube El thereby eliminating the stufiing.v

box. In that case, the pipe 'lli would be eliminated and gas from theintermitter would be admitted to one side of the piston il@ through thepipe lli and would operate to force the piston downwardly due to thedifference in areas of the opposite sides of the piston which produces adifferential pressure on the upper surface of the piston.

lit will be readily understood that huid under pressure is admitted tothe cylinder lit through the pipe liti to force the piston l@ to theupper end of its travel and thereby raise the valve piston Gili by meansof the rod t3 to the upper limit oit its travel. Upon cessation of thefluid pressure supply, that portion of the fluid trapped in the cylindertu may pass out through the bleed port 'lil and pipe l5 to a region ofreduced pressure, whereupon the weight of the valve piston titl and rod@il returns the piston to the lower extremity` of its travel.

The device is generally assembled as follows: The tubing 2l with theseat3u formed therein is lowered into the well casing 20, which already isset in the hole, until the bull plug 2t rests at or near the bottom ofthe well hole. The pump body t l which has been previously assembled,together with the valve piston 50 and rod 63 is lowered by means of thetubing string t2 until the seat t@ contacts the seat 30. The valveoperating machine M is then attached to the upper end of the rod t3 atthe Well surface.

In operation, liquid such as oil or water is -lorced from the producingstrata into the bottom hole under the normal rock; pressure and buildsup to a certain level in the well bottom at which time the headdeveloped is sufiicient to raise the standing valve 21 thereby admittingtheA liquid to the cham-ber 35 wherein it will assume its normal leveldependent upon the rock pressure existing in the producing strata. Thislevel will, of course, Vary in diierent wells. At this point actuatingiluid under pressure is admitted to the tubing 2l at the well surface.The pressure in this tubing is generally maintained at a near constantlevel, dependent upon the hydrostatic head of the :duid in the eductiontube which in turn is dependent on the well depth and fluid gravity.

At the same time fluid pressure from. the intermitter is admitted to themachine tt thereby raising the rod t3 and valve piston @d in a mannerheretofore'described. 'When the valve piston 6U reaches the upper limitof travel, gas under pressure in the tubing 2i passes through thepassage tt, port 45, port 65, chamber til, port tt, port tt, tube 54,aperture l, annular space 5t into the ,chamber 35 above the fluid leveltherein. The fluid pressure exerted upon the liquid surface forces thestanding valve 2li closed against the 'liquid pressure in the well andopens the standing valve 39 in the reducer di? whereby the liquid underurging by the uid pressure may pass up through the annular space betweenthe pump casing tt and the valve sleeve di, through the ports and intothe eduction tube t2.

The intermitter will generally-be set to maintain the valve piston inthe raised position long enough to allow a slug of gas to pass into theeduction tube below the slug of oil thus lightening the oil column,although this is not necessary to thev operation of applicants device.

Upon closing of the input valve by the intermitter, the valve pistonreturns under the action of gravity to the lower extremity of itstravel. In the lowered position, not shown in the drawings, the ports l5and it are closed thus closing oif the supply of uid under pressure tothe accumulation chamber, and at the same time the ports tti and @t areplaced in registry with the ports lll and dt, respectively.

llt will now be apparent that that portion oi the actuating gasentrapped under high pressure in the accumulation chamber 35, may passthrough the ports 52, tubes t5, ports lti, ports tt, chamber til, portstb, ports di, tubes titl, and ports tt to the annular space t@ andthence to the surface of the well. It is evident that as this proceduretaires place, the pressure in the chamber 35 is reduced to nearatmospheric. At this time the standing valve 3d closes and acts as acheck valve to prevent the return of liquid in the valve body di andeduction tube t2.

`When the pressure in the chamber 35 is bled to an extent that it issufciently lower than the liquid pressure within the well bottom plusthe force necessary to operate the standing valve tl, liquid from thewell bottom will again flow into the accumulation chamber.

After sumcient liquid has collected in the accumulation chamber, asdetermined by the normal well production, the intermitter again admitsfluid to the machine 64 to repeat the cycle.

It can now be appreciated that a series of slugs of/ fluid comprisingactuating gas and pumped liquid will be forced up through the eductiontube to the well surface from which it is conducted to the usualseparators andstorage tanks as will be understood by those familiar withthe operation of such wells. y

One important advantage of` the construction described above resides inthe fact that only so much of the actuating iluid as is trapped in theaccumulation chamber is exhausted to the surlface. In many previousdevices of this general type known to applicant, it has been necessaryto bleed the pressure iluld in the entire tubing string, and since thesestrings may be as long as six thousand feet or more, it will beappreciated that a great amount of gas pressure will be con- 'I5V servedwith a consequent lowering of the fluidliquid or gas-oil ratio and alarge increase in operating efficiency.

In the embodiment illustrated in'Figure 5, elements common to bothdevices are referred to by similar reference numerals.

In this form of applicants invention, the pump body indicated generallyat 80, differs in construction from the pump body of Figure 1, and theliquid eduction tube 32 is of a larger diameter. Only those parts whichdiffer from those previously disclosed and their mode of operation willbe set forth here.

'Ihe pump body 80 is provided with a shoulder 8| having a conical seat82 formed thereon to cooperate with the tubing seat 30 to form a sealbetween the annular space 58 and a chamber 83 formed between a reducedportion 84 of the pump body and the tubing string 2|, and is secured atits upper end to the tubing string 32 as by screwthreads 85.

The standing valve and cage 38 and 39 are secured to the pump body 80 bymeans of a pipe 86 and union 81 provided with a shoulder 88. A packing89 of any suitable material is placed between said shoulder and thelower end of the pump body.

A central bore 90 extends longitudinally of the pump body 80 andcommunicates at its lower end with the pipe 86 and at its upper end withthe eduction tubing 32.

Gas inlet bores 9| are formed in the pump body 80 and extendlongitudinally through the major portion thereof, communicating adjacenttheir upper ends with the inlet ports 92 and adjacent their lower endsWith the apertures 93, the extreme lower ends of said bores being sealedby the packing 89. A series of exhaust bores 94 surround the centralbore 90 intermediate the bores 9|. These bores extend from the lower'extremity of the valve body 80 and longitudinally thereof, to a pointadjacent the shoulder 8|, and communicate at one end with ports 95formed therein. Aniannular groove 96 interconnects the outer ends of theports 95 and is of largercross sectional area than the individual crosssectional areas of the ports 55 for the purpose set forth above indescribing the groove 56. Adjacent their lower ends the bores 94communicate with apertures 91 in communication with the chamber 35, andthe extremities thereof are sealed by the packing 89.

A spider 98 is secured to the lower end of the rod 63 as by nuts 99 andlock nuts |00, or in any suitable manner. each arm of the spider 98 andis secured thereto in like manner, and is slidably mounted in boresformed in the head |02 and shoulder 3| of the valve body 80. A stung box|03 in the head |02 seals the chamber 83 from the eduction tube 32.

Slide valves |04, secured to the valve rod as by pins |05, slide uponthe reduced portion 84 of the valve body and serve to close and open thegas inlet ports 92. A slide valve |06 in the form of a collar is securedto the lower ends of the valve rods |0| and is provided with valveinserts |01 suitably positioned Within the valve |06 and serving toclose and open the ports 91.

It should be noted that the valve collar |06 in its lower extremeposition will close the ports 91 but not the ports 93 because theinserts |01 are so -spaced to leave these ports open.

The device is assembled in the well in the same manner as that shown i-nFigure 1.

A valve rod |0| depends from l It will of course be understood that therod 63 is reciprocated by the means and in the manner previously setforth. Also, liquid will pass into the accumulation chamber 35 as in theformer device.

In operation,` actuating fluid under pressure is introduced between thetubing 32 and the tubing 2l from whence it passes into the chamber 83.

At this point the supply of gas will be cut off from the valve actuatingmachine, an opposite procedure to that previously described, whereuponthe slide valve |04 will be lowered to uncover the ports 92 and at thesame time the slide valve |06 will be lowered to close ports 91. Theactuating gas may now pass through the ports 92, bores 9|, and ports 93to the chamber 35 above the liquid level therein thus forcing the liquidthrough the standing valve 39, pipe 86, central bore 90 into theeduction tube 32. The gas is admitted until a slug passes into theeduction pipe below the oil slug as in the previous constructions.

Pressure gas will now be admitted to the rod actuating machine whichwill raise the rods, cover the ports 92 and open the ports 91. Theentrapped pressure gas can now pass through the apertures 91, bores 94,ports 95, and ports 56 to the annular space 59 and thence to the wellsurface and atmospheric pressure. As above set forth, liquid againpasses into the eduction chamber 35 and the cycle is repeated.

In the embodiment illustrated in Fig 6, the structure of Fig. is modiedto permit induction of actuating gas through the central tubing string32 and the eduction of liquid through the annular space between thetubing 32 and tubing 2|. v

To accomplish the above mentioned result, the pump body 80 is secured tothe tubing 32 at the shoulder 8| as by screwthreads and the head |02 isprovided with ports |08 in communication with the chamber 83. Thecentral bore 90 extends only partially through the pump body 80 and asecond port |09 places the bore 90 in communication with the annularspace utilized as a. liquid eduction passage.

In operation, actuating fluid under pressure is admitted to the tubing32 from whence it passes through the ports |08, chamber 83, ports 92(assuming that the slide valve |04 is lowered), bores 9|, ports 93 tothe accumulation chamber 35, thereby forcing the liquid therein throughthe pipe 86, central bore 90, and port |09 to the annular space betweentubing 32 and 2 After the chamber has been emptied of liquid and asuiiicient slug of gas has entered the eduction space, the valves |04and |06 are operated in the manner previously described to close theinlet port 92 and open the outlet port 91, whereupon the entrapped gasin the chamber may be exhausted as described in connection with theembodiment of Fig. 5.

I claim:

1. In a device of the class described, a Well, a tubing string includinga standing valve adjacent one end thereof, a seat formed in said stringspaced from said valve, a second tubing string within said first namedstring, a pumping element on said second named string provided with ashoulder cooperating with said seat to form a chamber for theaccumulation of liquid, said element having gas inlet ports formedtherein, a positively operated valve'adapted to close and open saidports to control the admission of gas to said chamber, and the saidsecond tubing string connecting with the chamber through the pumpingelement to serve as a liquid eduction pipe for the liquid being raisedfrom the Well.

2. In a device for raising liquid from a well, a tubing string includinga standing valve adjacent one end thereof, a seat spaced from saidvalve, a second tubing string within and spaced from said iirst namedstring, a pumping element attached to said second string and having ashoulder cooperating with said seat to form a chamber for theaccumulation of liquid,'said element having ports for the admission ofgas to said chamber, ports for the exhaust of gas thereand opening saidadmission and exhaust ports,

and the said second tubing string connecting with the chamber throughthe pumping element to serve as a liquid eduction pipe for the liquidbeing raised from the well.

3. In a pumping device of the class described, a tubing string adaptedto extend into a well, a valve adjacent one end thereof, a seat spacedfrom said valve; a second tubing string within said first named string;a pump element attached thereto and having a shoulder cooperating withsaid seat to form a closed chamber with said rst tubing string, a gasinduction conduit in said element communicating with said chamber, aliquid eduction conduit in said element joining said chamber and saidsecond named tubing string, a slide valve within said element adapted toopen and close said induction conduit, and` means for positivelyoperating said slide valve.

4. In a well pumping device, a tubing string extending within the well,a chamber at one end of the tubing string, a second tubing string withinsaid first named tubing string, a gas induction conduit in communicationwith said rst named tubing string and said chamber, a liquid eductionconduit in communication with said second tubing string and saidchamber, a gas exhaust conduit in communication with said cham- 'ber andthe exterior of said first named tubing string, valve means to controlthe admission and exhaust of gas lthrough said induction and exhaustconduits comprising a cylinder in the second tubing string and a pistonmember suspended independently of said second tubing string. 4

5. Ina well pumping device, a tubing string extending within the well, aliquid accumulation chamber at one end of the tubing string and solelysupported thereby, a second tubing string within and independentlyremovable from said first named string, a gas induction conduit incommunication with said second tubing string and said chamber, a liquideduction conduit formed by the space between the first named tubingstring and the exterior of the second string, said space being incommunication With the chamber, `a gas exhaust conduit in communicationwith said chamber and the exterior of said first namedA tubing string,and valve positively operated from the well surface to control theadmission and exhaust of gas through said conduits.

6. In a device for raising liquid from a well, a tubing string, a liquidaccumulation chamber adjacent the lower end of -said tubing string, a

second tubing string within the first named tub- Ying string, a pumpelement on said second tubing string, means providing a seal betweensaid element and said rst named tubing string to form a liquidaccumulation chamber, said second named tubing string being movablerelative to said first named string, a gas induction conduit in saidelement placing one of said tubing strings in communication with saidchamber, a liquid eduction conduit in said element placing the other ofsaid tubing strings in communication with said chamber, and valve meansfor controlling the admission of gas to said chamber positively operatedfrom the well surface.

7. In a device of the class described for raising liquid from a well, atubing string including a standing valve adjacent one end thereof, asecond tubing string within the iirst named tubing string, a pumpingelement on said second named string, means providing a seal between saidelement and said second string to form a chamber for the accumulation ofliquid, said element having gas inlet ports formed therein, ports in theelement connecting the said second tubing string with the chamber forthe eduction of liquid from the chamber, and a positively operated valveadapted to close and open said ports to control the admission of gas tosaid chamber.

8. In a device for raising liquid from a well, a tubing string includinga standing valve adjacent one end thereof, a second tubing string withinand spaced from said rst named string, a pumping element attached tosaid second string, means providing a seal between said pumping elementand said rst string to form a chamber for the accumulation of liquid,said element having ports for the admission of gas to said chamber,ports for the exhaust of gas therefrom, ports connecting the said secondtubing string with the chamber for the eduction of liquid from thechamber, and positively operated valve means for closing and openingsaid admission and exhaust ports.

9. In a pumping device of the class described, a tubing string adaptedto extend into a well, a valve adjacent one end thereof, a second tubingstring within said first named string, a pump element attached thereto,means providing a seal between said element and said iirst named stringto form a chamber for the accumulation of liquid, a gas inductionconduit in said element communicating with said chamber, a liquideduction conduit in said element joining said chamber and said secondnamed string, a valve within said element adapted to open and close saideduction conduit, and means for positively operating said valve.

10. In a device for -raising liquids from a well, a tubing stringincluding a standingvalve adjacent one end thereof, a second tubingstring within said first named string, a pumping. element on said secondnamed string, means providing a seal between said element and said firstnamed string forming a liquid accumulation chamber, said pumping elementhaving a cylinder formed therein, a series of ports in said cylinder, ahollow sleeve valve within said cylinder provided with a series of portsadapted to cooperate with said cylinder ports alternately to place saidchamber in communication with the interior and exterior of said iirstnamed tubing string for the admission of gas thereto and the exhaust ofgas therefrom, respectively, means for positively operating said valve,and a valved conduit in said element placing said chamber incommunication with said second tubing string for the eduction of liquidtherefrom.

11. In a device for raising liquids from a well,

a tubing string extending Within the well provided with a standing valveadjacent one end thereof, a second tubing string within said first namedstring, a pump element in said second string, a seal between said pumpelement and said rst named string to form a liquid accumulation chamber,said element having a gas induction conduit therein by-passing said sealto place said chamber in communication with said first named string, agas eduction conduit therein placing said chamber in communication withthe exterior of said rst named conduit, a liquid eduction conduittherein placing said chamber in communication with said second tubingstring, valve means located above said seal for controlling admission ofgas to said chamber, valve means below said seal for controlling theexhaust of gas from said chamber, and means positively operated from theWell surface simultaneously to open one valve and close the other.

JAMES E. HOOVER.

